Some snags for SLUB

> partial pages should be added to the tail of the list instead of the head.

Is it efficiency? I think adding the partial pages to the head is better, because it will give
the other partial pages more time to become free pages, and it will decrease the number of
partial pages. Anyhow, if the adding/deleting operations are too expensive, losing a little
space efficiency is just well, as Memory is cheaper than CPU. In the other way, adding to the
head will be cache friendly.

I wander that the test case exists in the real world.

:(